The object of the present invention is an autostabilizer device for a boat hull.
It generally relates to the industrial sector of the construction of boats of any dimensions and is designed to ensure the stability of boats with a “V”-shaped hull during maneuvers and displacements at very low speeds, or when stationary.
The current naval construction techniques have made it possible to make boats lighter and consequently to reduce their displacement, which is a factor of economy when running, but one of instability at low speeds, which is particularly true for “V”-shaped hulls, which have a good directional stability, but have to be loaded to be stable when stationary, which prevents the boats from being able to be made lighter to have a higher performance, because this stability depends on the position of the center of gravity to the center of buoyancy. It may be considered that the stablest boat is the lifebuoy because it does not have buoyancy at its center and in this case the stability is maximum when stationary.
To navigate comfortably, a boat has to comprise a “V”-shaped hull, in order to cut through the sea, the center of pressure and the center of gravity pass through the same axial point, and consequently, when stationary or at low speeds, such a boat lacks stability.
The prior-art devices tending to improve this stability without being a detriment to the behavior of the boat at high speeds have, in fact, only attempted to lessen the disadvantages of the “V”-shaped hull without being able to confer the stability of multihulls on them.
In some embodiments, water is used as a ballast to stabilize the boat when stationary, thanks to a tunnel or water ballast along the keel or in the hull, with a more or less large opening in the rear, which can be controlled and a vent at the prow. In these devices, the water does not drain out instantaneously when starting and the boat has to receive a more significant amount of energy to move, and if the water is preserved as a ballast, the increase in displacement requires a structural reinforcement, leading to a higher manufacturing cost and a higher consumption of energy.
The author of the present application has filed a plurality of patents, attempting to solve these problems, and in particular:                Patent No. FR 2 499 929 pertains to a boat combining a flat bottom with a “V”-shaped hull open in the front and in the rear. However, it has the drawback of only permitting the mounting of outboard-type motors and of requiring a great immersion depth of the propeller, which limits the application of the device to small-size boats. In addition, the tunnel, which is flush at the rear, has a high fragility and opposes a major resistance when running backwards.        Patent No. FR 2 650 550 describes a “V”-shaped hull comprising a flat, internal bottom forming with the said hull a stabilizing enclosure that is closed in the front, and provided with a vent emerging at the top part of the bow, the said enclosure being interrupted, with the transom plate recessed. However, this arrangement may only be applied to new boats and increases the cost of the boat to a considerable extent. In addition, due to its design proper, the enclosure changes the longitudinal balance of the boat when it is filled with water.        Patent No. FR 2 720 716 describes a boat consisting of a hull having a flat or concave bottom and an inverted “V”-shaped element, fitting detachably under the said hull to form a tunnel, interrupted with the transom plate recessed and closed in the front, whose center of gravity is more or less at the center of gravity of the boat, the said tunnel being able to be filled with water when stationary and to be drained when running thanks to the lateral vents. This device has the drawback of not being able to fit on a “V”-shaped hull.        